1. Field of the Invention
The present invention relates to a modified polymer and a composition containing the same. More particularly, the present invention is concerned with a first-order modified, hydrogenated polymer comprising (1) a hydrogenated polymer obtained by hydrogenating at least one unhydrogenated polymer selected from the group consisting of a polymer comprising conjugated diene monomer units and a copolymer comprising conjugated diene monomer units and vinyl aromatic hydrocarbon monomer units, and (2) a functional group-containing first-order modifier group bonded to the hydrogenated polymer (1), wherein the content of the vinyl aromatic hydrocarbon monomer units, vinyl aromatic hydrocarbon block ratio, weight average molecular weight, and hydrogenation ratio (as measured with respect to the double bonds in the conjugated diene monomer units) of the first-order modified, hydrogenated polymer are, respectively, within specific ranges. Further, the present invention is concerned with a second-order modified polymer obtained by reacting a second-order modifier with a first-order modified polymer comprising (β) a base polymer and (γ) a functional group-containing first-order modifier group bonded to the base polymer (β). Furthermore, the present invention is concerned with a composition comprising the above-mentioned first-order modified polymer or second-order modified polymer and at least one component selected from various conventional additives (such as inorganic fillers (e.g., silica), polymers other than the above-mentioned modified polymers of the present invention, tackifiers and asphalts). The modified polymer of the present invention exhibits strong interaction with other various components, and by virtue of such property, the modified polymer of the present invention can be advantageously used for producing compositions, such as a filler-containing modified polymer composition, a modified polymer composition comprising a thermoplastic resin and/or a rubbery polymer, an adhesive composition, an asphalt composition and a styrene resin composition, which have excellent properties. Furthermore, the present invention is concerned with a precursor composition for use as a precursor of a second-order modified polymer composition, wherein the precursor composition comprises a first-order modified polymer comprising a base polymer (β) and a functional group-containing first-order modifier group (γ) bonded to the base polymer (β), and further comprises a second-order modifier and at least one additional component selected from the group consisting of the above-mentioned additives.
2. Prior Art
As a method for producing a polymer having a functional group, Unexamined Japanese Patent Application Laid-Open Specification No. Sho 59-98106 (corresponding to U.S. Pat. No. 4,465,809) discloses a method for producing a carboxyl group-containing polymer, in which a polymer-alkali metal composition is contacted with an epoxy compound, and the resultant product is directly contacted with a cyclic acid anhydride, thereby obtaining a carboxyl group-containing polymer. However, such carboxyl group-containing polymer (which has a terminal epoxy compound residue having bonded thereto a cyclic acid anhydride residue) has poor affinity to a thermoplastic resin and/or a rubbery polymer, an inorganic filler, a polar group-containing additive and the like.
Unexamined Japanese Patent Application Laid-Open Specification No. Sho 63-238107 (corresponding to U.S. Pat. No. 4,972,023) discloses a polymer which is modified with a terminal acid group (or a salt thereof) which is bonded to the polymer through an acid amido group, and discloses a method for producing the modified polymer as well as applications of the modified polymer. This modified polymer is obtained by a method in which the modification is performed using 1,5-diazabicylo[3.1.0]-hexane and a derivative thereof and a Schiff base derived from an aliphatic or aromatic amine and aldehyde. The modified polymer (which is modified with a terminal acid group (or a salt thereof) which is bonded to the polymer through an acid amido group) has poor affinity to a thermoplastic resin and/or a rubbery polymer, an inorganic filler, a polar group-containing additive and the like.
Further, Unexamined Japanese Patent Application Laid-Open Specification Nos. Hei 7-196728 and Hei 9-143224 discloses a modified hydrogenated polymer which is obtained by introducing a primary amino group or a secondary amino group into the terminals of a hydrogenated polymer. However, such modified polymer (which is modified with a terminal amino group) has poor affinity to a thermoplastic resin and/or a rubbery polymer, an inorganic filler, a polar group-containing additive and the like.
In recent years, in the field of a tire tread rubber composition, a technique of using silica as a substitute for carbon black has been attracting much attention. However, this technique is accompanied by problems. For example, silica has poor affinity to a rubber as compared to that of conventional carbon black and, thus, the dispersibility of silica in a rubber is not always satisfactory. Such poor dispersibility of silica is likely to cause problems, such as unsatisfactory abrasion resistance and strength characteristics for a tire tread. For improving the dispersibility of silica in a rubber, it is necessary to add a silane coupling agent (typically bis(triethoxypropyl)tetrasulfide) to a composition of rubber and silica and mix the composition under specific temperature conditions, wherein the number of the mixing operations is increased.
In this situation, for improving the dispersibility of silica in a rubber, a method for modifying a rubber with various terminal alkoxysilyl groups, and a silica-containing rubber composition comprising the modified rubber have been proposed in Unexamined Japanese Patent Application Laid-Open Specification No. Sho 62-227908, Unexamined Japanese Patent Application Laid-Open Specification No. Hei 8-53513 (corresponding to U.S. Pat. No. 5,665,812) and Unexamined Japanese Patent Application Laid-Open Specification No. Hei 8-53576 (corresponding to U.S. Pat. No. 6,204,322).
Further, a silica-containing composition comprising an epoxidized polymer is proposed in Unexamined Japanese Patent Application Laid-Open Specification No. Hei 9-118785 (corresponding to EP763564). In addition, Unexamined Japanese Patent Application Laid-Open Specification No. Hei 7-330959 discloses a tire tread composition comprising an SBR (styrene-butadiene rubber) having a specific molecular structure, wherein the SBR has been modified by coupling a multifunctional compound having a diglicidylamino group. This tire tread composition was proposed in an attempt to provide a tire tread composition having increased processability, reduced rolling resistance and improved wet skid resistance.
The rubber material used in the above-mentioned rubber compositions has many unsaturated double bonds in the polymer chain thereof and, therefore, exhibits poor heat resistance and weatherability. As a conjugated diene polymer having excellent heat resistance and weatherability, Unexamined Japanese Patent Application Laid-Open Specification No. Sho 63-41547 discloses a hydrogenated polymer which is modified with a specific functional group. This patent document also discloses a method for improving the properties of a carbon-containing composition, in which a functional group (such as an amino group) which interacts with carbon is addition-bonded to a hydrogenated polymer. Further, WO96/05250 (corresponding to U.S. Pat. No. 5,804,644) discloses a silica-containing rubber composition comprising a hydrogenated rubber. However, the technique disclosed in this patent document is aimed at a rubber composition containing a rubber having low hydrogenation ratio which is suitable for producing tires. Therefore, the improvements in the heat resistance and weatherability of the rubber composition are unsatisfactory for use in fields other than tire production.
Unexamined Japanese Patent Application Laid-Open Specification No. Hei 2-60948 discloses a rubber composition having excellent heat resistance and weatherability. Further, each of Unexamined Japanese Patent Application Laid-Open Specification Nos. Sho 62-283105 and Sho 63-41547 and Unexamined Japanese Patent Application Laid-Open Specification No. Hei 3-74409 (corresponding to U.S. Pat. No. 5,216,074) discloses a hydrogenated modified polymer. The dispensability and reinforcing effect of silica which are imparted by the techniques disclosed in the above-mentioned patent documents are unsatisfactory and, moreover, the composition and polymer exhibit only poor properties with respect to processability, low heat build-up and abrasion resistance.
In the fields of sheets, films and other shaped articles which are produced from polymeric materials, there have been made a number of proposals in which there is used a polymer composition or laminate comprising a plurality of types of polymeric materials in order to obtain advantages in that a satisfactory strength is imparted to the sheets, films or the like, or the processability of the sheets, films or the like is improved, or the production cost of the sheets, films or the like is reduced. However, when producing a polymer composition by mixing different polymeric materials together, the number of combinations of different polymeric materials which exhibit good compatibility with each other, is limited. In the case of a polymer composition comprising different polymeric materials which exhibit poor compatibility with each other, a problem is likely to arise in that, due to the poor compatibility, the composition becomes non-homogeneous, and a delamination occurs between layers of different polymeric materials, thus rendering it impossible to obtain a satisfactory improving effect aimed at by using a combination of different polymeric materials.
It is well known that, as a component for improving the miscibility of polymeric materials, there is used a polymeric material having a functional group. For example, Unexamined Japanese Patent Application Laid-Open Specification No. Hei 2-60948 discloses a composition comprising a modified hydrogenated diene polymer having a functional group and a flexible elastomer, wherein the modified hydrogenated diene polymer is obtained by an addition reaction between a functional group-containing unsaturated compound and a hydrogenated diene polymer in the presence of a radical initiator. Further, Unexamined Japanese Patent Application Laid-Open Specification No. Hei 3-74409 (corresponding to U.S. Pat. No. 5,216,074) discloses a thermoplastic polymer composition comprising a modified hydrogenated block polymer having a functional group and a thermoplastic resin and/or a rubbery polymer, wherein the modified hydrogenated block polymer is obtained by an addition reaction between a functional group-containing unsaturated compound and a hydrogenated block polymer in the presence of a radical initiator.
An asphalt composition is used in wide variety of fields, such as a material for road paving, a waterproof sheet, a noise insulation sheet and a roofing sheet. In these fields, many attempts have been made to improve the properties of an asphalt by adding various polymers to the asphalt.
However, in recent years, due to the expansion of traffic and the increase in the number of expressways, there is a demand for an asphalt composition which can form a road pavement layer having excellent strength and abrasion resistance. Further, there is a growing demand for an asphalt composition which can form a road pavement layer having not only excellent strength and abrasion resistance, but also high open graded (void fraction) for improving drainage and noise reduction properties of expressways.
Recently, from the viewpoint of preventing environmental pollution and maintaining labor environment, the use of a hot-melt adhesive is expanding. However, the balance between retention and adhesion of the conventional hot-melt adhesive is unsatisfactory. For improving the properties of a hot-melt adhesive, each of Unexamined Japanese Patent Application Laid-Open Specification Nos. Sho 64-81877 and 61-278578 and “Sechaku (Adhesion)” Vol. 32, No. 1, page 27 (published in 1988) discloses an adhesive composition comprising a triblock copolymer and a diblock copolymer. However, the improvements achieved by the techniques disclosed in these patent documents were unsatisfactory.
A polystyrene having not only excellent stiffness, transparency and luster, but also good processability, is used in various fields. However, a polystyrene has a major defect, namely poor impact resistance. For alleviating this defect, various non-vulcanized rubbers are used as an impact modifier for a styrene resin composition. Among the known styrene resin compositions containing a non-vulcanized rubber, a styrene resin composition obtained by subjecting a styrene monomer to radical polymerization in the presence of a non-vulcanized rubber, which composition comprises a rubbery polymer having a styrene monomer graft-polymerized thereto, has been manufactured widely in commercial scale.
In connection with the above-mentioned method, a method for improving the impact resistance and appearance of a styrene resin composition by the use of a modified conjugated diene polymer has been disclosed in Unexamined Japanese Patent Application Laid-Open Specification Nos. Sho 57-94014, Sho 63-8411, Sho 63-278920 and Hei 6-228246. From the detailed studies of the methods disclosed in these patent documents, it became apparent that none of the produced styrene resin composition exhibit excellent balance between the impact resistance and appearance which is satisfactory for practical use.